System and method for dynamic identification of radio frequency transmission dead zones

ABSTRACT

A system and method are described that include pre-processing of user data at a mobile communication device prior to transmission of the user data to a cellular-connected server. Such pre-processing increases the efficiency of the cellular-connected server to permit near real time mapping of dead zones while maintaining a high degree of accuracy of the dead zone boundary.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 62/169,079, filed on Jun. 1, 2015, which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to nearly continuous dynamic identification ofradio frequency transmission dead zones.

BACKGROUND

Mobile communications devices are conventionally known. One challengewith mobile communication devices is identifying areas where radiofrequency transmission is insufficient for communication, which istypically described as a dead zone.

SUMMARY

This disclosure provides a system for mapping a radio frequency signaldead zone of a cellular system, the system comprising at least onecellular system antenna, a mobile communication device, and a firstcellular system processor. The at least one cellular system antenna isconfigured to transmit and to receive radio frequency signals. Themobile communication device includes at least one of a geographiclocation system receiver and a geographic location system device, amobile communication device antenna, a mobile communication deviceprocessor, and a non-transitory memory. The mobile communication deviceantenna is configured to transmit and receive signals from the at leastone cellular system antenna. The mobile communication device beingconfigured to determine by way of signals received by the mobilecommunication device antenna that the mobile communication device hasentered the radio frequency dead zone, and being configured to store inthe non-transitory memory location data received by the mobilecommunication device from the geographic location system receiver orlocation data determined by the geographic location system device. Whenthe mobile communication device is determined to leave the dead zone,the mobile communication device processor is configured to pre-processthe stored location data to generate a convex hull and to transmitsignals representing vertices of the convex hull to the at least onecellular system antenna. The first cellular system processor iscommunicatively connected to the at least one cellular system antenna,and is configured to receive the pre-processed location data transmittedby the mobile communication device and to create a concave hull map fromthe pre-processed data. The created concave hull map is transmitted byway of the at least one cellular system antenna to the mobilecommunication device for contemporaneous presentation on a display ofthe mobile communication device.

This disclosure also provides a method for mapping a radio frequencysignal dead zone of a cellular system. The method comprises determiningthat a mobile communication device has entered a dead zone; receivinggeographic location data of the mobile communication device from ageographic location data system or determining geographic location dataof the mobile communication device with a geographic location datadevice internal to the mobile communication device while the mobilecommunication device is in the dead zone; determining that the mobilecommunication device has left the dead zone; pre-processing thegeographic location data in the mobile communication device to generatea convex hull boundary having a plurality of vertices after determiningthat the mobile communication device has left the dead zone;transmitting the plurality of vertices of the convex hull boundary to aprocessor of the cellular system; aggregating at the processor thereceived plurality of vertices with other received pluralities ofvertices and processing the aggregated vertices to create a concave hullmap of the radio frequency dead zone; and transmitting the createdconcave hull map to the mobile communication device for contemporaneouspresentation on a display of the mobile communication device.

This disclosure also provides a system for mapping a dead zone of acellular system for presentation on a mobile communication device, thesystem comprising at least one cellular system antenna and a cellularsystem processor. The at least one cellular system antenna is configuredto transmit and to receive radio frequency signals. The mobilecommunication device includes at least one of a geographic locationdevice configured to determine location data and a geographic locationsystem receiver configured to receive location data; a mobilecommunication device antenna configured to transmit signals to andreceive signals from the at least one cellular system antenna; a mobilecommunication device processor; and a non-transitory memory. The mobilecommunication device being configured to determine from the receivedsignals whether the mobile communication device has entered the deadzone, and being configured to store in the non-transitory memorylocation data received by the mobile communication device. When themobile communication device is determined to leave the dead zone, themobile communication device processor is configured to pre-process thestored location data to generate a convex hull and to transmit verticesof the convex hull to the at least one cellular system antenna. Thecellular system processor is configured to receive the vertices from theat least one cellular system antenna and to create a concave hull mapusing the vertices, and the created concave hull map is transmitted toat least one user.

Advantages and features of the embodiments of this disclosure willbecome more apparent from the following detailed description ofexemplary embodiments when viewed in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a view of a system and a dead zone in accordance with anexemplary embodiment of the present disclosure.

FIG. 2 shows a block diagram of a mobile communication device of thesystem of FIG. 1.

FIG. 3 shows an enlarged view of the dead zone of FIG. 1 with stylizedlocation data points collected in the dead zone.

FIG. 4 shows a view of a first page of a process flow of the system ofFIG. 1 in accordance with an exemplary embodiment of the presentdisclosure.

FIG. 5 shows a view of a second page of a process flow of the system ofFIG. 1 in accordance with an exemplary embodiment of the presentdisclosure.

FIG. 6 shows a view of an optional process flow of the system of FIG. 1in accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Offline tracking by mobile communication devices has not been widelyadopted by users partially because storage space is at a premium on mostmobile devices and it is not feasible to store maps and metadata ofevery possible location at which a mobile communication device might bedisconnected from a cellular network. Currently, no system and methodexists that can efficiently and accurately map dead zones from user datain real time. Such a system and method could provide a significantadvantage to users of mobile communication devices by detectingproximity to a dead zone and then downloading smaller, more detailedmaps after predicting entry into the dead zone and downloading metadatato use while in transit through the dead zone. The detailed map couldenable the user of a mobile communication device to know what the deadzone looks like and which direction to travel to restore connection tothe cellular network.

An algorithm called an alpha-shape algorithm exists that includes thecapability of constructing dead zone boundaries based on user-supplieddata. However, the alpha-shape algorithm does not operate efficientlyenough on a large data set to be employed by a server to map dead zonesin real time. The present disclosure provides a system and method thatincludes pre-processing of user data at a mobile communication deviceprior to transmission of the user data to a cellular-connected server,thus increasing the efficiency of the cellular-connected server topermit near real time mapping of a dead zone while maintaining a highdegree of accuracy with respect to the boundary of the dead zone. Thisinformation is then fed back to the mobile communication device foralmost instantaneous access by the mobile communication device and/orthe end user of the mobile communication device.

Offline tracking systems and methods have grown significantly moreaccurate in recent years, yet still have not been widely adopted byusers for a variety of reasons. Among the reasons is the difficulty ofknowing with any degree of accuracy and precision the location of deadzones. Dead zones can change for a variety of reasons, includinghumidity, wind, foliation, atmospheric disturbances, electromagneticinterference, reflections of radio waves, etc. Such changes can move theboundaries of a dead zone by tens or even hundreds of feet in the courseof a day. Current systems for identifying dead zones require input of avast amount of data, and then lengthy processing of the data thatrequires many hours and even days to complete. By the time processing iscompleted, the boundary of the dead zone can be significantly differentfrom the boundary determined from data collected hours or days earlier.Since dead zone identification is not timely, it is perceived to beunreliable and is, accordingly, not widely used.

Another reason for the failure to widely adopt offline tracking is thata map of the relevant area may not be on the mobile communication devicewhen it enters a dead zone, at which point it is not possible to loadmaps of the dead zone and/or areas near the dead zone. In addition, itis typically not possible to preload detailed maps of all potentialareas a user might enter because storage space is at a premium on mostmobile devices. If a system and method existed to rapidly and accuratelymap dead zones, it would open the door for applications that couldautomatically detect when a mobile communication device approached adead zone, and download more detailed map data and metadata to use priorto reaching the dead zone for use within the dead zone. Even beyond thiscapability, accurately mapping dead zones would afford users much moreinformation about the boundaries of the dead zone and would enable usersto know the best direction to move to restore cellular networkconnection. Such a system could be entirely enabled and supported bypre-processed data from the mobile communication devices of users,making the users part of the system. Such a system would provide valueto those users as well as to cellular network providers by allowing thenetwork providers to gather contemporaneous data about the shape andlocation of dead zones. For the proposed system to work, the systemneeds to be configured to quickly and accurately parse user data and tomap the shapes and locations of the dead zones.

Historically, alpha-shapes have been widely used when trying to map aboundary from a set of data. Alpha-shapes are polygons that areconstructed from a set of location data points and correspond to aboundary of those location data points. For any set of location datapoints there is only one way to draw a convex polygon that is a boundaryof those location data points. The boundary of location data points iscalled a convex hull and although it can be used to map a boundary, itis not capable of creating a map that has concave sections.

Unlike a convex hull, there are multiple ways to draw or map a concavepolygon that is a boundary of a set of points. Because of the numerousapproaches to mapping a concave polygon, it is impossible to create analgorithm to draw a single perfect concave hull of a set of points.Instead, different concave hull configurations must be evaluated basedon some predetermined heuristic. The alpha-complex of a set of points isa triangulation of points based on such a heuristic. The alpha-complexevaluates all the triangles in a Delaunay Triangulation of the points bythe radius of their smallest enclosing circles and removes triangleswith a radius larger then 1/α. In other words, the alpha-complex removesthe longer, thinner triangles, leaving triangles which have sides thatare all similar lengths, creating a new triangulation that only connectspoints that are closer together. This removal process makes thetriangulation more likely to correspond to a boundary that tightlyencloses the set of location data points. The boundary of analpha-complex constructed this way is called an alpha-shape and itcorresponds to a concave hull of the set of points that is more likelyto reflect an actual boundary, which in the case of the presentdisclosure is a concave hull map.

Constructing an alpha-shape is a candidate for a system to map theboundary of a dead zone. However, because it takes O(n log n) time toconstruct an alpha-shape, alpha-shapes are usually used to process alarge amount of location data points only once, or are used to processslow moving data. The mathematical expression O(n log n) is a type ofmathematical expression described as big O notation. Big O notation isused in computer science to classify processes by how they respond tochanges in input size, particularly a growth rate in processing timewhen encountering increasing quantities of data. Constructingalpha-shapes to map the boundaries of dead zones is much too slow whenrapidly receiving data from users that can include hundreds to thousandsof location data points from each user. To efficiently and rapidly mapthe boundary of a dead zone, on the order of a second, it becomesnecessary to use a different algorithm or to find a way to keep thenumber of inputs relatively small to minimize the run time to constructalpha-shapes.

To describe an exemplary embodiment of the present disclosure, it isnecessary to first explain the context in which the embodiment would beused. The system algorithms would run on a server that takes input fromusers through an application or process that would run on a mobilecommunication device such as a smart phone. This application or processwould periodically ping or ask the server for information about thelocation of geographically near dead zones, and would store thatinformation in non-transitory memory of the mobile communication device.

The definition of near in this context can be adaptive based on travelconditions. For example, when a mobile communication device istravelling at a high rate of speed, such as 60 to 80 miles per hour, thedefinition of near can be, for example, up to five miles away, or apredetermined distance in a range from one to five miles, which providestime to download a dead zone map and metadata of relevance in the deadzone. As another example, when the mobile communication device istravelling at a low rate of speed, such as speeds up to 10 miles perhour, the definition of near can be, for example, 3,300 feet, or apredetermined distance in a range from about 800 feet up to 3,300 feet.

When the mobile communication device, based on data received from aserver connected to the cellular network, detects that it is close to adead zone, the mobile communication device would again contact theserver to download a map of the dead zone and the surrounding area. Ifthe mobile communication device gets disconnected, it would activateoffline tracking, for example, by using a GPS receiver, a pedestriandead reckoning system, a motion tracking system, or another offlinetracking system, and then periodically record its location and log thosepoints as inside the dead zone. Some offline tracking systems rely uponhardware within the mobile communication device, such as anaccelerometer, magnetometer, etc., that provide estimations of distancetravelled and direction of travel. Data logging would continue until themobile communication device is reconnected or non-transitory memoryavailable for data logging is filled. After the mobile communicationdevice is reconnected to the cellular network, the process transmitslocation data to the cellular network connected server. By ensuring thatthe process only transmits location data after the user is disconnectedand then reconnected to the cellular network, the system and methodensures that every user's location data includes at least two pointsthat will be close to the boundary of the dead zone, as the location atwhich the mobile communication device lost cellular network connectionand the location at which the mobile communication device regainednetwork connection should lie close to the boundary location of theactual, physical dead zone. Because at least some of the collectedlocation data points obtained by pre-processing remain as part of theset of location data points, the accuracy of a dead zone map isextremely high, as discussed in more detail hereinbelow.

Location data needs to be acquired within the dead zone for developmentof high-quality dead zone maps, described in more detail hereinbelow. Alimited number of location data can also be acquired just outside a deadzone boundary to further refine boundary positions more precisely. Morespecifically, since mobile communication device 30 is continuouslycollecting location data, once a dead zone entry is identified, alimited number, for example, 2-4 location data points, just outside thedead zone can be identified and stored in non-transitory memory as beingoutside the dead zone. Similarly, when exit from the dead zone isidentified, a limited number of location data points just or immediatelyoutside the dead zone boundary can be stored in non-transitory memory.The location data points on either side of the dead zone can be used ina closest pair process to identify boundary points of the dead zone, asopposed to hull vertices internal to the dead zone, duringpre-processing as a part of pre-processing.

Many aspects of the disclosure are described in terms of sequences ofactions to be performed by elements of a computer system or otherhardware capable of executing programmed instructions, for example, ageneral-purpose computer, special purpose computer, workstation, orother programmable data process apparatus. It will be recognized that ineach of the embodiments, the various actions could be performed byspecialized circuits (e.g., discrete logic gates interconnected toperform a specialized function), by program instructions (software),such as program modules, being executed by one or more processors (e.g.,one or more microprocessors, a central processing unit (CPU), and/orapplication specific integrated circuit), or by a combination of both.For example, embodiments can be implemented in hardware, software,firmware, microcode, or any combination thereof. The instructions can beprogram code or code segments that perform necessary tasks and can bestored in a non-transitory machine-readable medium such as a storagemedium or other storage(s). A code segment may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a class, or any combination of instructions, datastructures, or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data, arguments, parameters, or memory contents.

The non-transitory machine-readable medium can additionally beconsidered to be embodied within any tangible form of computer readablecarrier, such as solid-state memory, magnetic disk, and optical diskcontaining an appropriate set of computer instructions, such as programmodules, and data structures that would cause a processor to carry outthe techniques described herein. A computer-readable medium may includethe following: an electrical connection having one or more wires,magnetic disk storage, magnetic cassettes, magnetic tape or othermagnetic storage devices, a portable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (e.g., EPROM, EEPROM, or Flash memory), or any othertangible medium capable of storing information. It should be noted thatthe system of the present disclosure is illustrated and discussed hereinas having various modules and units that perform particular functions.

It should be understood that these modules and units are merelydescribed based on their function for clarity purposes, and do notnecessarily represent specific hardware or software. In this regard,these modules, units and other components may be hardware and/orsoftware implemented to substantially perform their particular functionsexplained herein. The various functions of the different components canbe combined or segregated as hardware and/or software modules in anymanner, and can be useful separately or in combination. Input/output orI/O devices or user interfaces including, but not limited to, keyboards,displays, pointing devices, and the like can be coupled to the systemeither directly or through intervening I/O controllers. Thus, thevarious aspects of the disclosure may be embodied in many differentforms, and all such forms are contemplated to be within the scope of thedisclosure.

Turning now to FIGS. 1-6, a system, indicated generally at 10 in FIG. 1,and method in accordance with an exemplary embodiment of the presentdisclosure is described. System 10 includes a cellular network 12, andcellular network 12 includes a plurality of cellular antennas 14supported by an antenna support 16, which can be, for example, acellular tower. Cellular network 12 also includes, or communicates with,at least a first server or processor 18. As will be seen, first serveror processor 18 can be connected to and communicate with a second serveror processor 20. System 10 further includes one or more mobilecommunication devices 30, each of which communicates wirelessly throughradio waves to cellular antenna(s) 14, and, accordingly, to first server18. Mobile communication device 30 can also communicate with an externalgeographic location system or mobile communication device 30 can includean internal geographic location device or system. The externalgeographic location system can be a system such as a plurality of GPSsatellites 22. Other geographic location systems can include the RussianGLONASS system, the Indian IRNSS/NAVIC system, the Chinese BeiDou-2tfsystem, the European Union Galileo positioning system, the Japanese QZSSsystem, and other systems that are capable of providing mobilecommunication device position or location data. Note that some of theaforementioned systems are in the development and/or deployment stageand as of the filing of this disclosure and some of these systems arenot yet operational or are not yet fully operational. The internalgeographic location device or system can include accelerometers and amagnetometer that provide signals to, for example, a pedestrian deadreckoning system, a motion tracking system, or other system internal tomobile communication device 30 for providing approximate location datafor mobile communication device 30 as device 30 moves through a deadzone. Mobile communication device 30 can be, for example, a smartcellular-enabled phone, a tablet, a laptop, or other electronic devicethat includes at least the ability to communicate with cellular network12 and GPS satellites 22.

FIG. 2 shows a block diagram of the elements or sub-systems of mobilecommunication device 30, which in the exemplary example of FIG. 2 is acellular enabled smart phone. Mobile communication device 10 includes ahousing or casing 32 which supports and positions a processor 34. Device10 further includes a radio frequency (RF) transceiver 36 and an antenna38. Processor 34 communicates with cellular network 12 by way of RFtransceiver 36 and antenna 38. Mobile communication device 10 canfurther include a sim card 40, non-transitory memory 42, a display 44,touch and/or pressure sensors 46, an accelerometer 48, a GPS receiver50, an A/D-D/A converter 52, a speaker 54, a microphone 56, and amagnetometer 58. Processor 34 is connected, directly or indirectly, toeach of these devices, and transmits signals to these devices, which caninclude control signals, receives signals from these devices, ortransmits and receives signals from these devices.

Mobile communication 10 can include non-transitory memory in more thanone location. In addition to non-transitory memory 42, sim card 40 caninclude non-transitory memory as can processor 34.

Processor 34 is also configured to transmit signals to speaker 16 and toreceive signals from microphone 56 by way of A/D-D/A converter 40.Non-transitory memory 42 can store processes for mobile communicationdevice 30 that can be transferred or communicated to processor 34 foroperation. Transceiver 36 can include a plurality of transceivers forcommunication by way of, for example, Wi-Fi, cellular network 12, andradio frequency identification (RFID). Transceiver 36 transmits signalsto and receives signals from antenna 38, which can include a pluralityof electrodes for transmitting and receiving signals in a plurality offrequency ranges.

Also shown in FIGS. 1 and 3 is a stylized dead zone 24. In the contextof this disclosure, a dead zone refers to a region where radio wavesignals that would otherwise be available from, for example, cellularnetwork 12, are of insufficient strength for reliable or anycommunication with cellular network 12.

Referring now to FIGS. 4-6, a dynamic dead zone identification process,indicated generally at 100, in accordance with an exemplary embodimentof the present disclosure is shown. As described elsewhere in thisdisclosure, current dead zone identification processes are timeconsuming and the results of such processes are delayed for hours oreven days after data is provided to the processes. In contrast, process100 analyzes location data, which is pre-processed by processor 34 ofmobile communication device 30 and then transmitted to first processor18, in seconds, providing rapid and, relative to current processes,contemporaneous data on the boundaries of dead zones. The ability todetermine a dead zone boundary from location data and transmit thatanalyzed data to a plurality of mobile communication device users withinseconds of receiving such data is dynamic as compared to conventionalprocessing.

At a start process 102, various portions of system 10 are initialized,and the processes necessary for the functions of system 10 aretransferred, for example, from non-transitory memory 42 to processor 34.Once system 10 is initialized, control passes from start process 102 toa location data process 104.

Process 100 includes a plurality of location data processes, includinglocation data process 104. Each location data process, including process104, operates in a similar or the same way. During location data process104, as with the other location data processes of process 100, locationdata is either generated internally to mobile communication device 30,or GPS receiver 50 receives signals from a plurality of GPS or othergeographic location system satellites 22 to identify the presentlocation of mobile communication device 30. For the sake of brevity,other location data processes will refer to location data process 104for description of functionality. Once location data has been internallygenerated or externally received from satellites 22, control passes fromlocation data process 104 to an RF signal process 106.

At RF signal process 106, mobile communication device 30 seeks an RFsignal and determines whether the signal from one or more cellularantennas 14 is adequate for RF communication. Control then passes fromRF signal process 106 to an RF signal decision process 108.

At RF signal decision process 108, if the RF signal is inadequate forcommunication with cellular network 12, control passes from RF signaldecision process 108 to a log location process 110, where the locationdata generated or received at location data process 104 is saved in, forexample, non-transitory memory 42 as a dead zone location. Control thenpasses from log location process 110 to a location data process 112,which functions similar to location data process 104, describedhereinabove. Control then passes from location data process 112 to an RFsignal process 114.

At RF signal process 114, which functions in a manner similar to RFsignal process 106, mobile communication device 30 again seeks an RFsignal and determines whether the signal is adequate for RFcommunication is available from one or more cellular antennas 14.Control then passes from RF signal process 114 to an RF signal decisionprocess 116.

At RF signal decision process 116, if an RF signal was not locatedduring process 114, control passes from process 116 to log locationprocess 110, which functions as described hereinabove. It should benoted that on return to log location process 110, the logged location isGPS location data generated or received at location data process 112,and the location data is saved in, for example, non-transitory memory 42as a dead zone location. If an RF signal was located during RF signalprocess 114, control passes from RF signal decision process 116 to apre-processing process 118.

At pre-processing process 118, all GPS location data in the dead zone ispre-processed. In an exemplary embodiment, the pre-processing takesplace in, for example, processor 34 of mobile communication device 30 toreduce the workload on first processor 18. However, the location datacould be downloaded to first processor or server 18 for transfer tosecond processor or server 20, where pre-processing can also take place.

Referring to FIG. 3, the first step in pre-processing process 118 is toidentify or define a convex hull or boundary 60 around all points 62that were logged as being inside dead zone 24. It should be noted thatconvex hull 60 includes a plurality of vertices 64 defined by theoutermost location data points 62. The number of location data pointsprior to pre-processing by processor 34 of mobile communication device30 can be a few hundred points to thousands of points. Afterpre-processing, the number of location data points is likely to be inthe range of 4 to 10, with 10 location data points being a preferredmaximum number of location data points. As discussed hereinabove,pre-processing can include location data points just outside boundary 26of dead zone 24, and a closest pairs process can be used duringpre-processing to determine the location of the dead zone boundary forthat particular set of data. Once pre-processing is completed, controlpasses from process 118 to a discard process 120.

At discard process 120, all location data points 66 internal or interiorto boundary or convex hull 60 are discarded. Though FIG. 3 shows arelatively small number of location data points 62, it should beunderstood that one mobile communication device 30 can store hundreds tothousands of location data points. Accordingly, discard process 120eliminates all but the location data points that define boundary orconvex hull 60, which substantially simplifies and speeds laterprocessing. Control then passes from discard process 120 to a datatransmission process 122.

At data transmission process 122, the location data points that defineconvex hull or boundary 60 are transmitted via antenna 38 to firstprocessor or server 18 of cellular network 12. Control then passes fromdata transmission process 122 to a concave hull process 124.

At concave hull process 124, the vertices of this convex hull receivedfrom mobile communication device 30 are added to previously recordedlocation data points. To limit the amount of data processed, only themost recent location data points from all mobile communication devices,which in an exemplary embodiment are in the range of 1,000 to 3,000 datapoints, are aggregated and retained for processing, and previouslocation data points are discarded. An alpha-shape representing the bestguess at a boundary 26 of dead zone 24 is then calculated using this newaggregate.

By pre-processing data at pre-processing process 122 on mobilecommunication device 30 and then creating boundary 26 at concave hullprocess 124 on a server or processor connected to the cellular network,which boundary 26 is a concave hull map, the relative error is estimatedto be approximately 10±4% as compared to a relative error of 6±5% usinga conventional alpha-shape process using all location data points, whichis considered acceptable for determination of dead zones for mobilecommunication device 30. The speed of processing to construct analpha-shape, after pre-processing 300 paths, each initially having 1,000location data points, down to approximately 10 location data points, isapproximately one second, which is a tremendous improvement in speedover a conventional alpha-shape process that requires an exponentialgrowth in speed of processing as the number of location data pointsincrease. Thus, system 10 and process 100 are able to provide anacceptable relative error with a processing speed that enables a dynamicmap of a dead zone, which, considering the minimal time needed forprocessing of the location data, is very near to real time. Because theconcave hull map is contemporary, near real time, the map can betransmitted to the user of mobile communication device 30 and be usefulto the user of device 30 to predict when the user will enter a mappeddead zone. Therefore, the user can determine whether to avoid the deadzone, or can obtain maps or data regarding locations within the deadzone prior to entry into the dead zone. Such maps or locations caninclude information about, for example, restaurants, service or gasstations, towns, retail establishments, etc.

Once processing to develop a concave hull alpha-shape is complete,control passes from concave hull process 124 to a map transmissionprocess 126, where a map of the dead zone is transmitted to mobilecommunication devices 30 that are relatively near to the dead zone. Nearin the context of this disclosure is described elsewhere herein. Oncemap transmission process 126 is complete, control passes to locationdata process 128, which functions in a manner comparable to locationdata processes 104 and 112, described hereinabove. Control then passesfrom location data process 128 through an off-page connector 130 to anon-page connector 132 in FIG. 5 and then to travel direction process134.

At travel direction process 134, mobile communication device 30determines whether a travel path, such as a travel path 68 shown in FIG.3, will intersect a dead zone, such as dead zone 24. All dead zone datacan be stored in, for example, first server or processor 18 or secondserver or processor 20. As mobile communication device 30 moves, severaloptions exist for downloading dead zone data. In an exemplaryembodiment, only dead zones within a predetermined distance, forexample, within 10 miles, are downloaded to mobile communication device30. In another exemplary embodiment, only the closest dead zone isdownloaded. In yet another exemplary embodiment, a predetermined numberof the closest dead zones, for example, 10, are downloaded. In anexemplary embodiment, travel direction process 134 can determine that atravel path will be within a predetermined distance of a dead zone. Suchinformation can be useful when a travel path includes, for example,turns that change a travel path from being in proximity or beingapproximately tangential to directly intersecting a dead zone within ashort distance. Once travel direction process 134 determines therelationship of a travel path to one or more dead zones, control thenpasses from travel direction process 134 to an intersection decisionprocess 136.

It should be observed that FIG. 3 also shows another travel path 70,which includes a convex hull or boundary 72 that bounds a plurality oflocation data points 74. Boundary 72 includes a plurality of vertices 64that are the only data transmitted to cellular system 12 after internallocation points 78 are discarded.

At intersection decision process 136, if, for example, travel path 68 ata location outside dead zone 24 does not intersect dead zone 24, controlpasses through an off-page connector 138 through an on-page connector140 in FIG. 4 to location data process 104, which functions as describedelsewhere in this disclosure. If travel path 68 does intersect dead zone24, as shown in FIG. 3, control passes from intersection decisionprocess 136 to an alert process 142.

At alert process 142, the user of mobile communication device 30 can bealerted, such as by way of speaker 54, display 20, or by other featuresof mobile communication device 30, that the user is approaching a deadzone. The user then has several options available. The user can reviewthe dead zone map received at map transmission process 126 and changedirection. The user can download predetermined data at a downloadprocess 144, which can be done automatically either with or withoutalert process 142. The predetermined data can include map metadataregarding locations within dead zone 24, and which can be located byusing location data acquired in one of the location data processes. Thepredetermined data can be the latest available dead zone map. The usermay elect to suspend an active call prior to entering the dead zone. Theuser may also use the dead zone map to determine approximately when thedead zone is exited or a fastest path through the dead zone. Once alertprocess 142 and download process 144, if used, are complete, controlpasses through off-page connector 138 to on-page connector 140 tolocation data process 104, which functions as described elsewhere inthis disclosure.

Because process 124 discards the oldest location data, there is a riskthat a dead zone contains both high travel areas and relatively lowtravel areas may be unable to maintain adequate definition of a deadzone. One option for accommodating a dead zone with high travel and verylow travel density areas is shown as an alternative embodiment concavehull process 124 a in FIG. 6.

Concave hull process 124 a begins by transferring pre-processed locationdata sets from first server 18 to second server 20 at a data transferprocess 150. Control then passes from data transfer process 150 to alocation data analysis process 152, which is performed at second server20. While second server 20 performs processes 152, 154, and 158,separate from first server 18, control at first server 18 passes fromdata transfer process 150 to a check data availability process 160,described in more detail hereinbelow.

At location data analysis process 152, second server 20 analyzes allavailable location data to determine whether a data density issueexists. For example, second server 20 can calculate the location datadensity of, for example, different portions of dead zone 24, anddetermine whether areas of very low data density exist. It should benoted that there are many options for determining location data density.For example, density can be randomly sampled. In another example, adensity map can be constructed and high and low values can be comparedto provide a guide in determining dead zones that may require additionalprocessing. Yet another way of monitoring data density is indirect. Ifdead zone boundaries fluctuate significantly with time, for example byan amount greater than 10% or 20%, first processor or server 18 orsecond processor or server 20 may flag the dead zone as potentiallyhaving significant variability in location data, and perform additionalanalysis to accommodate such variability.

If an area of dead zone 24 is identified that has such low location datadensity that those location data points may be discarded, second server20 can compensate for the location data that is potentially to bediscarded to avoid degradation of dead zone maps. Such compensation caninclude balancing selected data to prevent the deletion of data thatmight compromise portions of a concave hull dead zone map, dividing adead zone into two or more dead zones, or other types of compensation.Control then passes from location data analysis process 152 tocompensation decision process 154.

At compensation decision process 154, if no data density issues wereidentified in any dead zone, control passes from compensation decisionprocess 154 to an end process 156, which terminates process 124 a withinsecond server 20. If data density issues were identified in any deadzone and location data was adjusted to compensate for the data densityissues, control passes from compensation decision process 154 to a dataavailable process 158.

At data available process 158, a signal is transmitted to check dataavailable process 160 at first server 18, which indicates that locationdata that has been compensated for data density is available fortransfer from second server 20 to first server 18. Control then passesfrom data available process 158 to compensated data transfer process164, described further hereinbelow.

Returning to check data available process 160, control passes fromprocess 160 to a compensation available decision process 162. If firstprocessor 18 received a signal from second processor 20 that compensatedlocation data is available, control passes from compensation availabledecision process 162 to compensated data transfer process 164, wherelocation data that has been adjusted is transferred from second server20 to first server 18. Control then passes from compensated datatransfer process 164 to a concave hull map creation process 166, where aconcave hull map of one or more dead zones is created. It should benoted that transfer process 164 may not be an actual transfer oflocation data points, but can include a process for redefining a singledead zone to be a plurality of dead zones, and thus the separated deadzones can maintain boundary integrity when conditions are such thatportions of a combined dead zone might otherwise be eliminated due tothe relatively minimal amount of location data available.

Returning to compensation available decision process 162, ifcompensation for dead zones is unavailable, control passes fromcompensation available decision process 162 to concave hull map creationprocess 166, which functions as described elsewhere herein.

From concave hull map creation process 166, control passes to maptransmission process 126, which functions as described elsewhere in thisdisclosure.

Because processes 152-158 can require a substantial time to complete,process 124 a is configured to use existing location data at firstserver 18 rather than updated data from processes 152-158 untilprocessing of these steps at second server 20 is complete. Onceprocessing of revised location data in processes 152-158 is complete,then the compensation can be transferred from second server 20 to firstserver 18 prior to the creation of a new concave hull dead zone map,minimizing any delay in the rapid creation of contemporaneous dead zonemaps at first server 18.

While various embodiments of the disclosure have been shown anddescribed, it is understood that these embodiments are not limitedthereto. The embodiments may be changed, modified, and further appliedby those skilled in the art. Therefore, these embodiments are notlimited to the detail shown and described previously, but also includeall such changes and modifications.

I claim:
 1. A system for mapping a radio frequency signal dead zone of acellular system, the system comprising: at least one cellular systemantenna configured to transmit and to receive radio frequency signals; amobile communication device including at least one of a geographiclocation system receiver and a geographic location system device, amobile communication device antenna configured to transmit and receivesignals from the at least one cellular system antenna, a mobilecommunication device processor, and a non-transitory memory, the mobilecommunication device being configured to determine by way of signalsreceived by the mobile communication device antenna that the mobilecommunication device has entered the radio frequency dead zone and beingconfigured to store in the non-transitory memory location data receivedby the mobile communication device from the geographic location systemreceiver or location data determined by the geographic location systemdevice, and when the mobile communication device is determined to leavethe dead zone, the mobile communication device processor is configuredto pre-process the stored location data to generate a convex hull and totransmit signals representing the convex hull to the at least onecellular system antenna; and a first cellular system processorcommunicatively connected to the at least one cellular system antenna,the first cellular system processor configured to receive thepre-processed location data transmitted by the mobile communicationdevice and to create a concave hull map from the pre-processed data,wherein the created concave hull map is transmitted by way of the atleast one cellular system antenna to the mobile communication device forcontemporaneous presentation on a display of the mobile communicationdevice.
 2. The system of claim 1, wherein the first cellular systemprocessor is configured to transmit the concave hull map to the mobilecommunication device by way of the at least one cellular system antenna.3. The system of claim 2, wherein the mobile communication device isconfigured to determine whether a travel path of the mobilecommunication device is within a predetermined distance of or intersectsthe dead zone.
 4. The system of claim 3, wherein the mobilecommunication device is configured to provide an alert if the mobilecommunication device determines that the travel path intersects the deadzone.
 5. The system of claim 1, wherein the first cellular systemprocessor is configured to aggregate the pre-processed location datawith previously received pre-processed location data prior to creatingthe concave hull map.
 6. The system of claim 1, including a secondcellular system processor configured to identify areas of the dead zonedata with low density location data.
 7. The system of claim 6, whereinthe concave hull is adjusted for the presence of low density locationdata.
 8. The system of claim 1, wherein contemporaneous presentation isnear real time presentation.
 9. A method for mapping a radio frequencysignal dead zone of a cellular system, the method comprising:determining that a mobile communication device has entered a dead zone;receiving geographic location data of the mobile communication devicefrom a geographic location data system or determining geographiclocation data of the mobile communication device with a geographiclocation data device internal to the mobile communication device whilethe mobile communication device is in the dead zone; determining thatthe mobile communication device has left the dead zone; pre-processingthe geographic location data in the mobile communication device togenerate a convex hull boundary having a plurality of vertices afterdetermining that the mobile communication device has left the dead zone;transmitting the plurality of vertices of the convex hull boundary to aprocessor of the cellular system; aggregating at the processor thereceived plurality of vertices with other received pluralities ofvertices and processing the aggregated vertices to create a concave hullmap of the radio frequency dead zone; and transmitting the createdconcave hull map to the mobile communication device for contemporaneouspresentation on a display of the mobile communication device.
 10. Themethod of claim 9, including transmitting the concave hull map to themobile communication device by way of the at least one cellular systemantenna.
 11. The method of claim 10, including determining whether atravel path of the mobile communication device is within a predetermineddistance of or intersects the dead zone.
 12. The method of claim 11,including providing an alert if the mobile communication devicedetermines that the travel path is within a predetermined distance of orintersects the dead zone.
 13. The method of claim 9, includingidentifying areas of the dead zone data with low density location data.14. The system of claim 13, wherein the concave hull is adjusted for thepresence of low density location data.
 15. The system of claim 9,wherein contemporaneous presentation is near real time presentation. 16.A system for mapping a dead zone of a cellular system for presentationon a mobile communication device, the system comprising: at least onecellular system antenna configured to transmit and to receive radiofrequency signals; the mobile communication device including at leastone of a geographic location device configured to determine locationdata and a geographic location system receiver configured to receivelocation data, a mobile communication device antenna configured totransmit signals to and receive signals from the at least one cellularsystem antenna, a mobile communication device processor, and anon-transitory memory, the mobile communication device being configuredto determine from the received signals that the mobile communicationdevice has enter entered the dead zone, and being configured to store inthe non-transitory memory location data received by the mobilecommunication device, and when the mobile communication device isdetermined to leave the dead zone, the mobile communication deviceprocessor is configured to pre-process the stored location data togenerate a convex hull and to transmit vertices of the convex hull tothe at least one cellular system antenna; and a cellular systemprocessor configured to receive the vertices from the at least onecellular system antenna and to create a concave hull map using thevertices, wherein the created concave hull map is transmitted to atleast one user.
 17. The system of claim 16, wherein the mobilecommunication device stores location data points immediately outside thedead zone, and determines from a closest pair process the location of aboundary of the dead zone.
 18. The system of claim 16, wherein a map ofthe dead zone nearest to the mobile communication device isautomatically downloaded to the mobile communication device.
 19. Thesystem of claim 16, wherein map metadata for the area within a dead zoneis automatically downloaded to the mobile communication device whenproximity to the dead zone is detected.